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Chattopadhyay J, Mandal J, Maiti PK. Stability of the chiral crystal phase and breakdown of the cholesteric phase in mixtures of active-passive chiral rods. SOFT MATTER 2024; 20:2464-2473. [PMID: 38381111 DOI: 10.1039/d3sm01567j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
In this study, we aim to explore the effect of chirality on the phase behavior of active helical particles driven by two-temperature scalar activity. We first calculate the equation of state of soft helical particles of various intrinsic chiralities using molecular dynamics (MD) simulation. In equilibrium, the emergence of various liquid crystal (LC) phases such as nematic (N), cholesteric , smectic (Sm) and crystal (K) crucially depends on the presence of walls that induce planar alignment. Next, we introduce activity through the two-temperature model: keep increasing the temperature of half of the helical particles (labeled as 'hot' particles) while maintaining the temperature of the other half at a lower value (labeled as 'cold' particles). Starting from a homogeneous isotropic (I) phase, we find the emergence of 2-TIPS: two temperature-induced phase separations between the hot and cold particles. We also observe that the cold particles undergo an ordering transition to various LC phases even in the absence of a wall. This observation reveals that the hot-cold interface in the active system plays the role of a wall in the equilibrium system by inducing an alignment direction for the cold particles. However, in the case of a cholesteric phase, we observe that activity destabilizes the phase by inducing smectic ordering in the cold zone while an isotropic structure in the hot zone. The smectic ordering in the cold zone eventually transforms to a chiral crystal phase with high enough activity.
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Affiliation(s)
- Jayeeta Chattopadhyay
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
| | - Jaydeep Mandal
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
| | - Prabal K Maiti
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
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Bono S, Maruyama Y, Nishiyama K, Tabe Y. Heat-Driven Rigid-Body Rotation of a Mixture of Cholesteric Liquid Crystal Droplets and Colloids. J Phys Chem B 2020; 124:6170-6174. [PMID: 32558576 DOI: 10.1021/acs.jpcb.0c04186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We show that cholesteric (Ch) liquid crystal droplets with cylindrically symmetric orientation dispersing in an isotropic (Iso) phase exhibited unidirectional rotation under a heat flux along the symmetry axis. By introducing colloidal particle adhesive to the Ch droplet surface, we traced the translational motion of the colloids and found that the colloids rotated unidirectionally around the center of each Ch droplet. The director configuration of the droplets was not distorted either spatially or temporally, while the colloids rotated constantly. The results suggest that the Ch droplets under the heat flux should rotate as a rigid body. Using this heat-driven rotation of the Ch droplets, we designed new geometries of various composites of Ch droplets and colloids and succeeded in driving intriguing complex dynamics.
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Affiliation(s)
- Shinji Bono
- Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan
| | - Yuji Maruyama
- Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan
| | - Katsu Nishiyama
- Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan
| | - Yuka Tabe
- Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan
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Sasaki R, Takahashi Y, Hayashi Y, Kawauchi S. Atomistic Mechanism of Anisotropic Heat Conduction in the Liquid Crystal 4-Heptyl-4'-cyanobiphenyl: All-Atom Molecular Dynamics. J Phys Chem B 2020; 124:881-889. [PMID: 31880459 DOI: 10.1021/acs.jpcb.9b08158] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
All-atom molecular dynamics simulations were performed on 4-heptyl-4'-cyanobiphenyl (7CB) to study the mechanism of heat conduction in this nematic liquid crystal atomistically. To describe 7CB properly, the AMBER-type force field was optimized for the dihedral parameter of biphenyl and the Lennard-Jones parameters. The molecular dynamics calculation using the optimized force field well reproduced the experimental values of the isotropic-nematic phase transition temperature, density, and anisotropy of the thermal conductivity. Furthermore, the contributions of convection, intramolecular interaction, and intermolecular interaction to the thermal conductivity were determined by performing thermal conductivity decomposition analysis. According to the analysis, the contributions of convection, bond stretching, and bond bending interactions were higher in the direction parallel to the nematic director than that perpendicular to the director, which is the origin of the anisotropy in the nematic phase. This result indicates that the anisotropy is caused by well-aligned covalent bonds and high mobility parallel to the director. This quantitative description of the mechanism of heat conduction of 7CB is foreseen to provide new insights toward designing highly thermally conductive liquid-crystalline materials.
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Affiliation(s)
- Ryoma Sasaki
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology , Tokyo Institute of Technology , 2-12-1-E4-6 Ookayama , Meguro-ku, Tokyo 152-8552 , Japan.,Tokyo Tech Academy for Convergence of Materials and Informatics (TAC-MI) , Tokyo Institute of Technology , 2-12-1 Ookayama , Meguro-ku, Tokyo 152-8552 , Japan
| | - Yuki Takahashi
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology , Tokyo Institute of Technology , 2-12-1-E4-6 Ookayama , Meguro-ku, Tokyo 152-8552 , Japan
| | - Yoshihiro Hayashi
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology , Tokyo Institute of Technology , 2-12-1-E4-6 Ookayama , Meguro-ku, Tokyo 152-8552 , Japan.,Research Institute of Polymer Science and Technology (RIPST) , Tokyo Institute of Technology , 2-12-1 Ookayama , Meguro-ku, Tokyo 152-8552 , Japan
| | - Susumu Kawauchi
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology , Tokyo Institute of Technology , 2-12-1-E4-6 Ookayama , Meguro-ku, Tokyo 152-8552 , Japan.,Tokyo Tech Academy for Convergence of Materials and Informatics (TAC-MI) , Tokyo Institute of Technology , 2-12-1 Ookayama , Meguro-ku, Tokyo 152-8552 , Japan.,Research Institute of Polymer Science and Technology (RIPST) , Tokyo Institute of Technology , 2-12-1 Ookayama , Meguro-ku, Tokyo 152-8552 , Japan
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Nozawa T, Brumby PE, Yasuoka K. Effect of Central Longitudinal Dipole Interactions on Chiral Liquid-Crystal Phases. Int J Mol Sci 2018; 19:ijms19092715. [PMID: 30208651 PMCID: PMC6164681 DOI: 10.3390/ijms19092715] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 09/05/2018] [Accepted: 09/06/2018] [Indexed: 12/03/2022] Open
Abstract
Monte Carlo simulations of chiral liquid-crystals, represented by a simple coarse-grained chiral Gay–Berne model, were performed to investigate the effect of central longitudinal dipole interactions on phase behavior. A systematic analysis of the structural properties and phase behavior of both achiral and chiral systems, with dipole interactions, reveals differing effects; strong dipole interactions enhance the formation of layered structures; however, chiral interactions may prevent the formation of such phases under certain conditions. We also observed a short-ranged smectic structure within the cholesteric phases with strong dipole interactions. This constitutes possible evidence of presmectic ordering and/or the existence of chiral line liquid phases, which have previously been observed in X-ray experiments to occur between the smectic twisted grain boundary and cholesteric phases. These results provide a systematic understanding of how the phase behavior of chiral liquid-crystals changes when alterations are made to the strength of dipole interactions.
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Affiliation(s)
- Takuma Nozawa
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
| | - Paul E Brumby
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
| | - Kenji Yasuoka
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
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Sarman S, Wang YL, Laaksonen A. Thermomechanical coupling in coarse grained cholesteric liquid crystal model systems with pitches of realistic length. Phys Chem Chem Phys 2016; 18:16822-9. [DOI: 10.1039/c6cp02972h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cholesteric liquid crystal where the director is rotated by a temperature gradient.
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Affiliation(s)
- Sten Sarman
- Department of Materials and Environmental Chemistry
- Arrhenius Laboratory
- Stockholm University
- 106 91 Stockholm
- Sweden
| | - Yong-Lei Wang
- Department of Materials and Environmental Chemistry
- Arrhenius Laboratory
- Stockholm University
- 106 91 Stockholm
- Sweden
| | - Aatto Laaksonen
- Department of Materials and Environmental Chemistry
- Arrhenius Laboratory
- Stockholm University
- 106 91 Stockholm
- Sweden
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Metere A, Sarman S, Oppelstrup T, Dzugutov M. Formation of a columnar liquid crystal in a simple one-component system of particles. SOFT MATTER 2015; 11:4606-4613. [PMID: 25959363 DOI: 10.1039/c5sm00570a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report a molecular dynamics simulation demonstrating that a columnar liquid crystal, commonly formed by disc-shaped molecules, can be formed by identical particles interacting via a spherically symmetric potential. Upon isochoric cooling from a low-density isotropic liquid state the simulated system underwent a weak first order phase transition which produced a liquid crystal phase composed of parallel particle columns arranged in a hexagonal pattern in the plane perpendicular to the column axis. The particles within columns formed a liquid structure and demonstrated a significant intracolumn diffusion. Further cooling resulted in another first-order transition whereby the column structure became periodically ordered in three dimensions transforming the liquid-crystal phase into a crystal. This result is the first observation of a columnar liquid crystal formation in a simple one-component system of particles. Its conceptual significance is in that it demonstrated that liquid crystals that have so far only been produced in systems of anisometric molecules can also be formed by mesoscopic soft-matter and colloidal systems of spherical particles with appropriately tuned interatomic potential.
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Affiliation(s)
- Alfredo Metere
- Department of Materials and Environmental Chemistry, Stockholm University, S-106 91, Stockholm, Sweden.
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Yoshioka J, Ito F, Suzuki Y, Takahashi H, Takizawa H, Tabe Y. Director/barycentric rotation in cholesteric droplets under temperature gradient. SOFT MATTER 2014; 10:5869-5877. [PMID: 24866557 DOI: 10.1039/c4sm00670d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
When a chiral liquid crystal is given a transport current, a unidirectional molecular motion is known to take place, which is called the Lehmann effect. In this paper, we study the mysterious heat-current-driven Lehmann effect using two types of hemispherical cholesteric droplets using polarizing, reflecting, confocal and fluorescent microscopies. Both the droplets, coexisting with the isotropic phase and contacting on a glass substrate, are characterized by the concavo-convex modulated surface and the inside orientational helix. Further, the only difference between them is the helical axis direction; i.e., one is perpendicular and the other is parallel to the substrate. Under the temperature gradient perpendicular to the substrate, the droplet whose helical axis is parallel to the heat current exhibited pure director rotation, while that with the axis perpendicular to the current rotated independently as a rigid body. In the two droplets, the rotational conversion efficiency from the temperature gradient into the angular velocity showed very different dependences on the chirality strength and on the droplets' size, suggesting that the rotations of the two droplets may be driven by independent torques with different origins. This is the first observation that the cholesteric droplets under the temperature gradient exhibit the two rotational modes, the pure director rotation and the molecular barycentric motion, which can be switched to each other by changing the heat-current direction parallel and perpendicular to the helical axis.
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Affiliation(s)
- Jun Yoshioka
- Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
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Metere A, Oppelstrup T, Sarman S, Laaksonen A, Dzugutov M. Formation of the smectic-B crystal from a simple monatomic liquid. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:062502. [PMID: 24483463 DOI: 10.1103/physreve.88.062502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Indexed: 06/03/2023]
Abstract
We report a molecular dynamics simulation demonstrating that the smectic-B crystalline phase (Cry-B), commonly observed in mesogenic systems of anisotropic molecules, can be formed by a system of identical particles interacting via a spherically symmetric potential. The Cry-B phase forms as a result of a first-order transition from an isotropic liquid phase upon isochoric cooling at appropriate number density. Its structure, determined by the design of the pair potential, corresponds to the Cry-B structure formed by elongated particles with the aspect ratio 1.8. The diffraction pattern and the real-space structure inspection demonstrate dominance of the ABC-type of axial layer stacking. This result opens a general possibility of producing smectic phases using isotropic interparticle interaction both in simulations and in colloidal systems.
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Affiliation(s)
- A Metere
- Department of Materials and Environmental Chemistry, Stockholm University, Arrhenius Väg. 16C S-106 91 Stockholm, Sweden
| | - T Oppelstrup
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94551, USA
| | - S Sarman
- Department of Materials and Environmental Chemistry, Stockholm University, Arrhenius Väg. 16C S-106 91 Stockholm, Sweden
| | - A Laaksonen
- Department of Materials and Environmental Chemistry, Stockholm University, Arrhenius Väg. 16C S-106 91 Stockholm, Sweden
| | - M Dzugutov
- Department of Mathematics and Centre for Parallel Computers, Royal Institute of Technology, S-100 44 Stockholm, Sweden
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